Mainly talking about "experiencing self-cultivation in the process of creation",
He distinguished this school from stage craft and performance art and called it experiential art.
The chapters are very detailed, covering all aspects of stage performance, such as imagination, realism and belief, communication, self-feeling, highest task, consistency of action, speed and rhythm, control and decoration, stage charm and so on. In addition to talking about the morality of actors.
In a word, it's about stanislavski's playing system.
I hope my answer can help you a little.